In drive units for internal pipeline equipment, that is, equipment which is used within the interior of a pipe or pipeline and which must be capable of traveling through the length of the pipe or pipeline, the drive motors, usually pneumatic or hydraulic, have conventionally been disposed with their axes transverse to the pipe axis and in line with or parallel to the drive wheels of the drive unit. This relationship between the driving wheels and the drive motors which drive them limits the utility of such apparatuses to pipes of relatively large diameter, because the lengths of the pneumatic or hydraulic motors which must be used are such that drive units could not be designed for use in relatively small diameter pipes. For example, in U.S. Pat. No. 3,747,394 and U.S. Pat. No. 3,979,941 the drive motors of the drive units shown are disposed aligned with the drive wheels and transverse to the pipe axis, and such devices could not be designed for use in relatively small diameter pipes.